Several devices for utilizing the rise and fall of the tides or wave action to impart motion to mechanical systems are well known in the prior art. For example, such devices are the subjects of U.S. Pat. Nos. 378,452; 603,314; 1,036,502; 1,455,718; 1,623,341; 2,484,183; 3,268,154; 3,690,790; 3,697,764; and 3,925,986. The last of such listed patents contains a summary description of several of the earlier listed patents and is a particularly useful background reference. So as not to be unnecessarily repetitive, only those listed patents not summarized in U.S. Pat. No. 3,925,986 will be summarized below.
U.S. Pat. No. 603,314 provides for an apparatus for using tidal motion to compress air. The apparatus comprises a vertical standard having a centrally pivotally mounted beam supported thereon, the pivotal mounting permitting the beam to rotate in a vertical plane, a float attached to one end of the beam and a piston driven air compressor attached to the other end of the beam. U.S. Pat. No. 603,314 does not suggest the use of a tide to create an air pressure or vacuum or the use of such a pressure/vacuum to drive a pair of fluid-coupled reciprocating piston rods.
Another system for using wave motion to compress air is shown in U.S. Pat. No. 1,036,502, in which a large platform is used as a float, and cylinders anchored below the platform operate directly as air compression cylinders with piston rods secured to the float platform. This patent does not suggest a low pressure/partial vacuum system used to drive a pair of reciprocating, fluid-communicated cylinder rods, as exemplified by my invention.
U.S. Pat. No. 1,455,718 shows a hydropneumatic device actuated by waves, including a submergible chamber having a water entrance and an outlet for the air displaced by the entering water, means to collect such air and an automatic system for raising and lowering the chamber according to the state of the tide in order to pump air from the chamber, under pressure. None of the features of my invention described in the two preceding paragraphs are present or suggested in this patent.
U.S. Pat. No. 2,484,183 discloses still another device for using a tide to compress air and to create a partial vacuum, both of which are employed to drive a turbine. The system shown incorporates a main tank in which the changing water level causes air pressure to correspondingly vary; an auxiliary tank connected to the main tank through a one-way check valve, the auxiliary tank being used to hold pressurized air; and a suitably valved port for supplying air at atmospheric pressure to the main tank when partial vacuum conditions exist therein. Both the latter port and an outlet port from the auxiliary tank are connected directly to an air driven turbine. As with the aforementioned patents, U.S. Pat. No. 2,484,183 lacks the essential combination of elements characterizing my invention.
A tide driven power generator operated by both pressure and partial vacuum is also disclosed in U.S. Pat. No. 3,925,986. A valve is used to control the direction of air flow to the turbine, which is dependent upon whether positive pressure or partial vacuum is being used to activate the turbine, the valve being controlled by a diaphragm member responsive to air pressure changes in the tidal chamber attributable to the raising or lowering of the tide. Among other notable distinguishing features, my present invention employs a two-state valve means permitting either positive air pressure or partial vacuum to drive the system, the status of the valve being controlled by the physical position of the driven components rather than by a pressure differential.